Cats is the fifth work of musical theatre mastermind Andrew Lloyd Webber (the never-performed "The likes of US" aside), renowned for its longevity and popularity, if not necessarily for its actual content. The musical is possibly the best known in the world, at least from the modern era, most of the other contenders also being Webber productions.

Cats has been performed by stationary and touring companies in several dozen countries, and spun off a (slightly condensed) video version, but most attention tends to fall on the New York and London runs. The London run began in the New London Theatre on May 11, 1981, and ended 21 years later to the day, as the longest-running musical in England, with 8,950 showings under its belt. It would have been the longest-running theatrical performance of any kind in the country if not for Agatha Christie's The Mousetrap, the longest-running play in the world, continually showing since 1952. The American run was conducted in the Winter Garden Theatre on Broadway from October 7, 1982 to September 10, 2000, for a total of 7,485 performances, at the time the longest-running Broadway show in history. (This title would be stolen by Webber's The Phantom of the Opera in early 2006.)

The concept and musical numbers of Cats are adapted pretty faithfully from T.S. Eliot's book of children's poetry, Old Possum's Book of Practical Cats, although the Grizabella plotline which serves as the basis of several songs, including Memory, the show's biggest number, was taken from some of Eliot's unpublished work. Webber wrote the music and Trevor Nunn was chosen to work on the lyrics, which caused some tension with Tim Rice, whom Webber had worked with since he was 17, though the two were somewhat estranged at the time.

As Possum was mostly a collection of character sketches, so is Cats, albeit in musical form. Many "Jellicle" cats, a term defined several various ways in the play but never clearly and definitively explained, have gathered in a junkyard for the annual Jellicle Ball. Here their leader, Old Deuteronomy, will choose one to ascend to the Heaviside Layer, presented as a sort of feline heaven, and be reborn. The lives of several cats, presumably contenders for this honor, are described in song, trickster Macavity kidnaps Old Deuteronomy, who must be rescued, and eventually Grizabella, a sad, tattered female who once left the Jellicles and now seeks to return, is chosen.

That's really all there is - not very complex, and not particularly loved by theatre critics (being theatre critics), it made a virtue and drawing point of its simplicity and accessibility, and relied for its longevity in large part on tourists. Like the Parthenon, or the Eiffel Tower, if you were visiting London or New York, seeing Cats was just something you did. Vaguely resented for inspiring a "dumbing down" of musical theatre, it's at least grudgingly respected in some quarters for serving as millions' first encounter with musicals, sparking new interest in the genre.

Cats has a central cast of 24, with scores more among the chorus and dancers. All perform in intricate makeup and yak hair costumes that the show is particularly known for - the costumes are very detailed and realistic, even up close, as when the production calls for the actors to wander about the seats acting catlike, and strike a good balance between the desire to highlight the characters' feline grace and beauty and the pragmatic need for anthropomorphism. The junkyard sets are likewise complex, and their contribution to performances should not be underestimated. Built larger-than-life for a sense of proportion and wonder, the sets also included several dynamic elements, with the inclusion of such pieces as the deck of a pirate ship and a tire lifted on a hydraulic column for the final ascent to the Heaviside Layer forcing the Winter Garden Theatre stage to be torn down and purpose-rebuilt for the show. The lauded layout is generally considered to have sparked a trend towards the grandiose in musical theatre set design, and served as the inspiration for such later stage crew headaches as the helicopter landing in Miss Saigon.

*The order, lyrics, and even existence of some of the songs, as well as some character names, differ slightly between the American and British runs. Shows in other countries are conducted in the native language.